In certain video disc systems, information is prerecorded on a video disc record in a spiral track or groove. The information is recovered by a track-following stylus which senses geometric variations of the track on the surface of the record as capacitive variations between a conductive electrode on the stylus and a conductive property of the record surface. In one preferable system the stylus is contoured to engage the spiral groove. The stylus is mounted to a stylus arm attached via a compliant coupling to a carriage assembly which is driven to translate the stylus radially across the disc during normal playback operations. The compliant coupling permits limited relative motion between the stylus and the carriage assembly.
In normal playback the stylus progresses along the groove in a continuous manner as the carriage assembly translates. In addition to the normal playback it is desirable to provide special effects controlled by the user or preprogrammed on a special disc for over-riding normal playback progression. These special effects may include repeat play of a single or plurality of groove convolutions or scanning. The special effects may be implemented by translating the stylus from one groove convolution to another. In a video disc system such as the RCA Model SGT350 it was thought that because the record tracks or grooves are shallow, i.e., in the order of 1 .mu.m, and the stylus pressure low, e.g., 60-100 milligrams, little or no damage to the record would occur as the stylus crosses between convolutions during these special effect stylus translating operations. In fact, although this method does work, it has, on occasion, shown some tendency to damage the disc surface.